The mechanism by which fluoride exhibits the growth of cultured L cells is unknown, and this response will be studied. Experiments during the next year will concentrate on a determination of the effect of fluoride on the rate of metabolic flux of various metabolizable substrates through the cells. The metabolic basis for the previously demonstrated influence of fluoride ingestion on the rate of gastric emptying will also be investigated by studying influence of fluoride on lipid metabolism within tissues of the gastrointestinal tract.